The invention is in the area of determining the presence of biological masses on foliage. In particular, the invention is directed to a method and apparatus for automatic counting of insect egg masses on foliage samples. The United States has rights in this invention and the patent issued therefor.
Spruce budworm infestations are classified and defoliation predictions are made for the following year based on the number of new egg masses found on host-tree foliage during a current year. In Maine, egg mass surveys for the eastern spruce budworm, Choristoneura fumiferna (Clem), are routinely done in mid-July and August. Branch samples are cut from the host balsam fir, Abies balsamea (L) Mill., with extendable pole pruners. The branches are then transported to a central laboratory where they are examined visually for budworm egg masses.
The examination process is very tedious and time consuming. The accuracy of finding and counting egg masses may be adversely affected by the budworm population level, nature of the foliage examined, and the worker's experience. Additional factors such as boredom and fatigue tend to further limit accuracy and efficiency.
Daniel T. Jennings, in an article entitled "Using Black Light to Find Jack-Pine Budworm Egg Masses", USDA, Forest Service Research Note NC-56, (1968), discloses that egg masses of the jack-pine budworm (C. pinus pinus Freeman) and the eastern spruce budworm (C. fumiferana (Clem)) fluoresce when excited by long wave ultraviolet (UV) light. A similar phenomenon was observed for egg masses of the western spruce budworm (C. occidentalis Freeman) and was reported in an article by Robert E. Acciavatti and Daniel T. Jennings entitled "Locating Western Spruce Budworm Egg Masses With Ultraviolet Light", USDA, Forest Service Research Note RM-313 (1976). Fluorescence under UV light can aid examiners in locating and counting egg masses more quickly than under ordinary day light illumination. Both studies conclusively demonstrate that accuracy of egg mass examination can be increased by inspection of foliage illuminated by UV light.
When large numbers of foliage samples must be examined for their egg mass content, the problems are greatly multiplied. Even though the improved UV light manual methods require so many man-hours of personnel time to do the actual hands-on counting, most large forest surveying is impracticle. Also, the tedium of manual counting of large samples contributes to even greater inaccuracies in the count due to both mental and physical fatique.
Furthermore, direct exposure to UV light by personnel who do large volume manual counting for an extended period of time, may be undesirable because of possible side effects upon a person's skin and eyes.